The earth's magnetic field at a certain point is 0.70 gauss. This field is to be annulled by the magnetic field at the centre of a circular conducting loop 5.0 cm in radius. The required current is about

Question

The earth's magnetic field at a certain point is 0.70 gauss. This field is to be annulled by the magnetic field at the centre of a circular conducting loop 5.0 cm in radius. The required current is about (A) 0.66 A (B) 5.6 A (C) 0.28 A (D) 2.8 A

Tardigrade Admin · Accepted Answer

The magnetic field at the centre of closed loop is

B = \frac{μ _{0} I}{2 r} = \frac{4 π \times 1 0 ^{- 7} \times I}{2 \times 5 \times 1 0 ^{- 2}}

or

0.70 \times 1 0^{- 4} = \frac{4 π \times 1 0 ^{- 7} \times I}{10 \times 1 0 ^{- 2}}

∴ I = 5.6 A

Q. The earth's magnetic field at a certain point is $0.70$ gauss. This field is to be annulled by the magnetic field at the centre of a circular conducting loop $5.0 c m$ in radius. The required current is about

$0.66 A$

$5.6 A$

$0.28 A$

$2.8 A$

The magnetic field at the centre of closed loop is
$B = \frac{μ _{0} I}{2 r} = \frac{4 π \times 1 0 ^{- 7} \times I}{2 \times 5 \times 1 0 ^{- 2}}$
or $0.70 \times 1 0^{- 4} = \frac{4 π \times 1 0 ^{- 7} \times I}{10 \times 1 0 ^{- 2}}$
$∴ I = 5.6 A$

Q. The earth's magnetic field at a certain point is 0.70 gauss. This field is to be annulled by the magnetic field at the centre of a circular conducting loop 5.0cm in radius. The required current is about

0.66A

5.6A

0.28A

2.8A